Liquid semi-permeable membrane columns (or semi-permeable membrane columns) are commonly used in laboratory for washing, separating, or purifying biological molecules, such as DNA, RNA, and proteins. Semi-permeable membrane columns that are commonly used are mostly cylindrical in shape, whereby the bottom is provided with one or more pieces of semi-permeable membranes of special purposes. The column is infused with liquid, and an adequate force is then applied to the liquid in the column, forcing the liquid out of the column through the semi-permeable membranes.
Normally, the applied force can be a centrifugal force or air pressure. When centrifugal force is used, the column is usually placed in a liquid collecting tube, and then the liquid is infused in the column. The liquid collecting tube and the column are then placed into a centrifuge. The centrifuge is turned on to spin at high speed to generate a high centrifugal force. The liquid in the column is forced out of the column through the semi-permeable membranes and collected in the liquid collecting tube. The above process is only suitable for a single column. When an operation involving numerous columns is needed, the process would become overly cumbersome as the capacity of a centrifuge is limited. When air pressure is employed as an applied force, numerous semi-permeable membrane columns can be inserted into a vacuum manifold, which has a greater capacity than a centrifuge. By applying a positive or negative air pressure, the liquid is forced out of the columns through the semi-permeable membranes and is collected in the vacuum manifold. The process of using air pressure is more convenient when operating numerous samples or continuous operations.
A conventional semi-permeable column 31 (see FIG. 1) generally comprises three parts: an upper cervical section 311, a middle tubular section 312, and a lower tapered section 313. The diameter of the upper cervical section 311 is larger than that of the middle tubular section 312. Some of the columns include a lid 314. The middle tubular section 312 is provided for containing liquid sample, and its internal bottom part includes one or more specific purposed semi-permeable membranes (not shown in the figure). Some of the columns have a design of lower tapered sections 313.
As shown in FIG. 1, the engagement of the traditional semi-permeable membrane column 31 with a vacuum manifold 32 is in a tight insertion style: the lower tapered section 313 of the liquid semi-permeable membrane column 31 is inserted into a hole 34 of the vacuum manifold 32 directly or via an insertable adaptor column 33. The insertable adaptor column 33 is used to avoid direct insertion of the semi-permeable membrane column 31 into the hole 34 of the vacuum manifold 32, as the hole 34 of the vacuum manifold 32 may come in contact with the sample contained in the semi-permeable membrane column, and such can lead to cross contamination amongst different samples. The insertable adaptor column 33 can be of a disposable type or can be easily cleaned for repeated use. When the insertable adaptor column 33 is used, the lower tapered section 313 of the semi-permeable membrane column 31 is inserted into the insertable adaptor column 33. Then this ensemble is inserted to the hole 34 of the vacuum manifold 32, and forms the following structure from top to bottom: the semi-permeable membrane column 31—the insertable adaptor column 33—the vacuum manifold 32. Many applications utilize the insertable adaptor column 33, especially experiments which require no cross contamination of the samples, such as using purified nuclear acid for PCR reaction. It is therefore very important that this engagement must be tightly secured to avoid any gas leakage. Often, an operator has to hand-hold the semi-permeable membrane column 31 and the insertable adaptor column 33 to ensure tight engagement. It is likely that the operator may experience discomfort at the fingers due to this maneuver. On the other hand, as can be better understood by referring to FIG. 1, the semi-permeable membrane column 31 remains protruding outwardly from the apparatus during operation, and it is inserted into the hole 34 merely at its tip. Thus, it can easily become disengaged from the hole 34 due to any unintentional collision.
To overcome the above disadvantages, the applicant proposed an invention, which has been allowed as TW 253957. This invention provides an apparatus for processing biological sample, in which a semi-permeable column can be easily placed in the slot of a vacuum manifold. In cases where the liquid to be processed is highly contagious, an adaptor column can be used to avoid cross-contamination and to prevent the operator coming in direct contact with the liquid sample. During operation, the semi-permeable column is placed in the adaptor column, and the adaptor column is placed in the slot of the vacuum manifold. In doing so, the operator can easily operate the apparatus, and even repeated perform the operations without causing pain to the operator's fingers.
According to TW 253957, the semi-permeable column is loosely received in the slot of the vacuum manifold before air pressure or vacuum is applied. If an adaptor column is introduced between the semi-permeable column and the slot of the vacuum manifold, the gaps existing between the two columns and between the adaptor column and the slot will render that the adaptor column is loosely received in the slot and that the semi-permeable column is loosely received in the adaptor column. Due to the gaps, the semi-permeable column and/or the adaptor column can become unstable during operation, and the accuracy of tests will thus be adversely affected.
In view of this, the applicant makes improvement on TW 253957. In the improved apparatus, a seal having the effect of sealing and securing the column in position is provided such that when the semi-permeable column in placed in the slot of the vacuum manifold, air-tight condition can be maintained between the column and the slot, and that the semi-permeable column and the adaptor column will be secured in position without shaking and shifting during operation, and the accuracy of test results can be secured.